Definition
An exclamation used to express surprise, shock, or concern.
天啊
Oh Lord, I've forgotten my keys at home!
天啊，我把鑰匙忘在家裡了！
Oh Lord, you're really moving that far away.
老天，你真的要搬到那麼遠的地方嗎？
Good Lord, did you see that car almost hit the pedestrian?
天啊，你看到那輛車差點撞到行人嗎？